The Brooklands aeroscreens and the replica Auster ones (and the originals) are adjustable for angle. So as they can lie flat, I'd think that even if normally one had to look though, they'd still not be regarded as a windscreen and need wipers in the UK.
Melvyn Rutter has sold, I think a new car, with Brooklands Aeros fitted and the normal deflectors removed. Looked quite nice from the photo I saw.
